1. Field of the Invention
This invention concerns a thin mesh and a method and device for producing that mesh. More specifically, it concerns a thin mesh produced by a high-density microscopic mesh process, a method for producing such a thin mesh using an ultraviolet beam, and a device for producing such a thin mesh.
2. Related Art
FIG. 26 is a simplified cross section of a common design for an inhaler (atomizer) 101, which creates a spray by means of ultrasonic vibration. Fixed to the upper portion of casing 104, inhaler 101 has a mesh 102 containing numerous microscopic holes 103, as pictured in FIG. 27. The upper surface of the mushroom-shaped vibrator 105 is pressed against the lower surface of mesh 102, and the bottom of vibrator 105 is immersed in liquid medicine 107, which is kept in reservoir 106. In the center of vibrator 105 and traversing its length is suction tube 108.
When vibrator 105 is made to vibrate up and down, mesh 102, pressed with an appropriate force by vibrator 105, resonates with the same microscopic vibration. When mesh 102 resonates, negative pressure is generated between the mesh and vibrator 105. This causes the liquid medicine 107 in tank 106 to be sucked through tube 108 to the upper surface of vibrator 105. The medicine 107 which is sucked to the region between mesh 102 and vibrator 105 passes through microscopic holes 103 when mesh 102 vibrates, and vaporized medicine 107 is sprayed into the air.
Because the mesh 102, which is used in the inhaler 101 described above, requires that medicine 107 be atomized (i.e., vaporized), the numerous holes 103 which constitute the mesh must be sufficiently minute, as shown in FIG. 27. For this reason, the material used for the mesh must be exceedingly tough and resistant to corrosion. In addition, because of the use to which it will be put, a medical device such as inhaler 101 must use a material which is resistant to chemicals and safe for humans.
Methods to produce a mesh 102 with microscopic holes 103 using a single process include electroforming, etching and the electron discharge method. However, if mesh 102 is to be produced by electroforming, only certain specific metals such as nickel can be used, resulting in poor anti-corrosive properties. (Gold and some other metals could also be used, however these are expensive.) Since heavy metals pose a safety risk for humans, a mesh 102 made from nickel could not be used in medical equipment, and its uses are limited. A mesh which is safe for human beings can be achieved by plating the surface of nickel mesh 102 with another metal. However, since it is impossible to completely eliminate the formation of pinholes in the metal plating, it is not possible to completely prevent leaching of the nickel.
When an inhaler 101 as described above is used, the effective delivery of the drug to the affected part varies with the diameter of the particles of spray. This diameter is profoundly influenced by the shape and the cross-sectional contour of the holes 103 in the mesh. Because the mesh 102 in an inhaler 100 as described above must resonate with vibrator 105, the thickness of the mesh is constrained by the frequency of vibrator 105.
When the mesh is produced by electroforming, there is a correlation between the thickness of the mesh material and the cross-sectional shape of holes 103. The shape of the holes is limited by the thickness of the mesh, and in fact the only possible form for holes 103 is the hemispheric cross sections shown in FIG. 28. Because it is difficult to process holes 103 along their depth to achieve a desired result, it is not possible to achieve the most desirable cross-sectional contour for holes 103.
With the electroforming method, both the arrangement of holes 103 and their shape must be regular, as shown in FIG. 27; an irregular arrangement of holes 103 is not a possible design.
When the mesh is formed by etching or by the electron discharge method, it is extremely difficult to vary the diameter of holes 103 along their depth. The holes produced by these methods are completely straight, as shown in FIG. 29. It is not possible to form holes in mesh 102 of any other desired cross-sectional shape. Holes 103 could not, for example, be made to taper significantly.
This invention is developed in view of the shortcomings of the examples of the prior art discussed above. Its objective is to provide a mesh and a production technology for that mesh which would not be limited as to materials, provided the materials are thin enough. This mesh would be able to use a material with superior anti-corrosive properties and chemical resistance, yet which would be safe for human beings. The shape of the holes in this mesh and their cross-sectional contour could be selected as needed.